spirv: Use NIR per-member splitting

Before, we were doing structure splitting in spirv_to_nir.
Unfortunately, this doesn't really work when you think about passing
struct pointers into functions.  Doing it later in NIR is a much better
plan.

Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Acked-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/amd/vulkan/radv_shader.c

@@ -266,6 +266,13 @@ radv_shader_compile_to_nir(struct radv_device *device,
 		 * lower the rest of the constant initializers.
 		 */
 		NIR_PASS_V(nir, nir_lower_constant_initializers, ~0);
+
+		/* Split member structs.  We do this before lower_io_to_temporaries so that
+		 * it doesn't lower system values to temporaries by accident.
+		 */
+		NIR_PASS_V(nir, nir_split_var_copies);
+		NIR_PASS_V(nir, nir_split_per_member_structs);
+
 		NIR_PASS_V(nir, nir_lower_system_values);
 		NIR_PASS_V(nir, nir_lower_clip_cull_distance_arrays);
 	}